Rapid tire deflation has been a problem since the dawn of the automobile. Rapid deflation can cause accidents on the road leaving a driver and passengers stranded in inhospitable situations. Various devices have been invented to prevent or mitigate the loss of air pressure in tires.
A tire that can be run after loss of or reduction in pressure has been a desirable objective in the tire industry for some time. A tire that can be run in a deflated condition for an appreciable distance permits the driver to continue after the loss of or reduction in pressure or until a replacement tire can be obtained or the damaged tire repaired. This would eliminate changing tires on the road and the need to depend on the serviceable condition of a spare tire that takes up considerable space in the vehicle. Also, such a safety tire would permit the driver to continue on some distance until a safe stopping place could be found thus avoiding sudden stopping on crowded, streets, bridges and highways. Many pneumatic tire constructions have been designed in an attempt to achieve these capabilities such as the constructions of U.S. Pat. Nos. 3,095,917, 3,392,772 and 3,724,521, however, none have been wholly successful in meeting the operational demands of current automotive vehicles.
U.S. Pat. No. 4,008,743 to Welch shows a pneumatic tire with an internal toroidal safety structure that expands and provides emergency support between the tire tread and the wheel rim if the tire loses inflation pressure. The safety structure has an outer circumferential belt comprising one or more superposed layers of cord reinforced strips, the belt being secured to the safety structure in a relatively narrow central circumferential zone so that radial expansion of the toroidal safety structure is readily accommodated should the tire lose inflation pressure. The belt bears between the inner surface of the tread portion of the tire and the safety structure in the event of tire deflation or underinflation and thus guards against puncture.
The internal safety structure of the Welch inflatable tube or resilient toroidal member with special reinforcing means can be bulky and make tire changes cumbersome. Safety structures introduced inside of the tire are subject to the rotational acceleration and vibration forces due to tire rotation from ordinary use and bumps on the road. Double inner tubes, solid rubber tires and related structures greatly complicate tire balancing, add weight and make tire maintenance more cumbersome. The tire construction of the present invention, however, reduces these difficulties.